Samsung Galaxy Tab – the latest iPad competitor to hit the quickly-crowding tablet market – is already available through Verizon, T-Mobile, and Sprint. And as of this weekend, the sleek, flatscreen device is also available on AT&T. The AT&T-issue Galaxy Tab will sell for $649; consumers will not have to sign up for any sort of contract to get their hands on the machine.

PC World has a pretty good breakdown of the data plans available for the Samsung Galaxy Tab, and it's well worth clicking through if you're considering purchasing the device. Here's the CliffsNotes: AT&T offers the cheapest monthly data plan, at $15 for 250MB. By comparison, T-Mobile charges $25 for 200MB of data per month. (T-Mobile, of course, offers the Galaxy Tab at the subsidized price of $400 if consumers sign a data contract.)

The Samsung Galaxy Tab has earned generally solid marks from reviewers, despite its 7-inch screen, which Apple CEO Steve Jobs has publicly derided as too small for most users. In a positive review of the Galaxy Tab in the New York Times, David Poguenoted that "Samsung sweated the details on this thing. The screen is gorgeous. The touch response is immediate and reliable. The whole thing is superfast and a pleasure to use."

Still, for now the tablet market seems to belong to Apple, which has sold about 7.5 million iPad units in less than a year. On Friday, Brian Marshall, an analyst with the firm Gleacher and Company, stirred up a media tempest when he predicted that Apple will release in 2011 an "iPad 2." Apple has not commented on the rumor, but the company has in the past refreshed its products on a regular basis.